With advancement in the semiconductor industry there is a need to utilize new precursor materials that will meet stringent film requirements. The precursors are used in wide-ranging applications for depositing semiconductor layers. For example, the solid precursors may include components for the barrier, high k/low k dielectric, metal electrode, interconnect, ferroelectric, silicon nitride, or silicon oxide layers. Additionally, the solid precursors may include components acting as dopants for compound semiconductors. Some of the new materials are in solid form at standard temperature and pressure and cannot be delivered directly to the semiconductor film deposition chambers for the manufacturing process. Exemplary precursor materials include those inorganic and organo-metallic compounds of Aluminum, Barium, Bismuth, Chromium, Cobalt, Copper, Gold, Hafnium, Indium, Iridium, Iron, Lanthanum, Lead, Magnesium, Molybdenum, Nickel, Niobium, Platinum, Ruthenium, Silver, Strontium, Tantalum, Titanium, Tungsten, Yttrium, and Zirconium. These materials generally have very high melting point and low vapor pressure, and must be sublimed within narrow temperature and pressure ranges prior to introduction to a deposition chamber.
Technologies have been developed for subliming solid precursor materials for semiconductor manufacturing processes. A solid sublimator system is conventionally used to produce solid vapor for deposition. Due to the variety of the solid precursors, with independent sublimation temperature and pressure ranges, a sublimator and delivery system is preferably capable of flexible operational parameters. Preferably, the sublimator is configured to vaporize the precursors at the desired temperature and pressure and to deliver the precursors without contamination to the deposition chamber.
Currently, there are several types of solid sublimators commercially available for the industry. In one application, the solid precursors are collected and freely piled inside a container compartment. The compartment is heated to an elevated temperature, and inert carrier gas is introduced into the compartment to carry the sublimed vapor phase downstream for film deposition. While cost effective, this application may result in carrier gas that is not saturated or a precursor vapor concentration that is not stable in the carrier gas. Further, the contact time between the carrier gas and the solid precursors are significantly reduced due to the consumption of the solid and the channeling flow through the agglomerated solid particles after operation for a period. As a means to compensate for this shortcoming, and for reducing contact time between carrier gas and solid, an agitation structure is installed inside the compartment to agitate the solid continuously. The agitation structure is designed to prevent the solid from agglomeration at operation condition, eliminate the channeling flow, and maintain sufficient contact of carrier gas with solid. However, the agitator fails to reduce contact time sufficiently, due to the consumption and/or the height of the precursor solids piled inside the container. Additionally, the movable part of the agitator decreases operational efficiency, increases maintenance downtime, and creates the concern of leakage and safety.
Another conventional application in the industry includes a solid precursor coated on the surfaces of various structures. For example, the solid precursor can be coated on cylinder surfaces that are set concentrically inside a heated container for sublimation. The surfaces may suffer non-uniformly distributed temperature profiles along the surfaces and, therefore, a non-stable sublimation of solid, resulting in a non-stable vapor concentration of precursor materials. Alternatively, the coated surface may be installed on a rotating shaft. The coated surface can be spot heated for smooth sublimation of solid precursors. However, the vaporization rate with this device is limited to low carrier gas flow rates. The carrier gas flow rate may not be feasible for industrial scale operational needs.
Recently, attempts to distribute solid materials on fluidicly coupled, heated surfaces inside a container or compartment have been implemented. In this application, the carrier gas flows through a number of passageways configured to couple the gas glow path between/through the heated surfaces. The carrier gas is routed from a lower heated surface, through the passageways to an upper layer or level. In certain applications, the carrier gas carries sublimed precursor vapor from a bottom surface of the heating surface to a top surface via the passageways. However, in order to maximize sublimation efficiency and surface area of the heated surface, a high number of passageways may be necessary. In these applications, the passageway diameters are minimized to maximize the heated surface area. The small diameter passages are easily clogged by small particles falling from the heating surface or unintended deposition of the precursor materials in the passageways.
Consequently, there is a need in the industry for a solid precursor sublimator for the sublimation of solid precursors with short contact time, high flow rate, low maintenance, for the production of a stable, saturated carrier gas.